I did hear / read NOT to use to much antifreeze {ie 50/50 works and no stronger} as it looses its performance if no diluted... how true that is i dont know
Water has a very high specific heat capacity, in fact essentially the second highest, after ammonia. That is in other words how much energy it takes to raise its temperature by a given amount. So in the case of a cooling system, how much heat it can carry away.
Propylene glycol, Ethylene glycol or indeed any of the main active ingrediants in antifreeze have a fairly low specific heat capacity, so a system full of that would be great at protecting it against freezing but would struggle to carry the heat away when the engine was hot as it requires much less energy per unit than water to raise it's temperature the same amount.
In an ideal world coolant would be 100% water, but this would obviously freeze, boil sooner, setup a corrosion nightmare and would not lubricate the water pump (the slightly oily property of the glycol helps to lubricate the pump).
In hot countries the ideal mix is just enough antifreeze so that the anticorrosive properties work, and also to help increase the boiling point - I believe it is possible to get a boiling point increaser/anticorrosive.
A dot of washing up liquid or better washing machine powder (NOT DISHWAHER) is ideal to help "wet" (reduce surface tension) the water, in otherwords help it to get closer to the surface of the metal in the engine and radiator and help to transmit the heat. It also cuts through any oily bits on the block head removing hot spots.